Process of concentrating ores



Aug. 19, 1924. I 1,505,323

B. EBERENZ 'PROCESS OF CONCENTHATING ORES Original Filed April 15.1920

I'm/enter G'ewyefilzeren z Z7 JMM m Cir Patented ug. 19, W24.

STAES GEORGE B. EBERENZ, OF EL PASO, TEXAS, ASSIGNOR OF ONE-FOURTH TO EDWARD P.

MATHEWSON, OF NEW YORK, N. Y., AND 'I'HREE-FOURTHS TO THOMAS J. SCAN- LON, O'F ALTON, ILLINOIS.

PROCESS OF CONCENTBATING ORES.

Application filed April 15, 1920, Serial No. 874,077. Renewed January 5, 1924.

To all whom it may concern:

Be it known that I, GEORGE B. EBEnENz, a citizen of the United States, residing at El Paso, in the county of El Paso and State of Texas, have invented certain new and useful Improvements in Processes of Concentrating Ores, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part hereof.

The present invention is directed to improvements in processes of concentrating ores by flotation, the object sought being to produce a mineral froth floatable on, the surface of the pulp under treatment by subjecting the pulp to the action of sulfureted hydrogen gas or other reducing or non-oxygenous reagent while the pulp is undergoing agitation in asuitable container, without the use of selective agents such as frothing oils or oily substances usually depended on to segregate the mineral components (mainly sullids) from the nonmineral particles or gangue. To produce a coherent froth carrying the mineral particles without resort to frothing oils, the reagent employed must be delivered to the pulp (except perhaps during the last stages of the operation) without access of atmospheric air in order to avoid possible oxidation of any sulfid mineral particles, and to facilitate and ensure the desired reactionbetween the oxidized mineral particles and the active element (sulfur) of the reagent be subjected to the action of the gas under pressure maintained in contact with the surface of the pulp while the latter is (preferably) mechanically agitated, the agitation being necessary to ensure a thorough impregnation and aeration of the pulp mass by the gas, or at least a suflicient impregnation and aeration to effect the frothing which is needed to concentrate the mineral particles of the ore. By my process oxiof the operation, the frothing being facilitated in the majority of cases, by keeping the pulp as nearly neutral as. possible by means of lime, caustic alkali, or equivalent reagent, though a slight acidity with some ores is not harmful. In order to determine how much sulfureted hydrogen shall be employed to produce an ideal mineral-gas froth, the following observations as to oil flotation will be pertinent. In oil flotation air plays a very lmportant part in the formation of the bubbles which result in the final froth. At the same time in what is today recognized as .an ideal oil flotation process dependence is had on the presence of a fraction of one per cent of oil (on the ore) which, as well understood in the art has a preferential aflinity for the mineral particles when in the-form of sulfide.

This aflinity is no doubt due to the reaction between the sulfur of the minerals and the hydrogen of the oil resulting in the formation of sulfureted hydrogen which is recognized as a reducing agent, and as such it no doubt plays an important part in preventing oxidation of the mineral particles by the air with which the pulp is charged and by which they are floated, oxidation of the mineral particles destroying or materially impairing the affinity which the oil manifests therefor when the same are in the form of sulfids. By my process, in lieu of forming the sulfureted hydrogen by the reaction above indicated (between the sulfur of the mineral sulfids and the hydrogen of the oil) I, introduce this reagent into the froth, it being understood that the sulfids of most of the metals are heavier than the oxids though having a greater affinity for the aerating gases than have the ox1ds. In my process a certain degree of elasticity may be imparted to the froth by the addition to the pulp of a small quantity (a pinch) of rosin inpowdered form, the presence of the rosin likewise assisting an the frothing operation. It was pointed out above that except at the later stages of the process, the operation shouldv be carried on without access of atmospheric air. In this connection it may be stated that inert gases such as nitrogen, carbonic acid and the like are not only not deleterious but tend to assist the frothing presumably for the reason that they do not oxidize the mineral particles sulfidized by the sulfureted hydrogen. These inert gases may come from the atmosphere, or, in the case of carbonic acid gas, this may be evolved from the mineral and other carbonates contained in a pulp to which a slight quantity of acid (mineral acid) has been added to bring about neutralization of an alkaline pulp, or purposely added to slightly acidify a neutral pulp, it being understood that while I prefer to operate on a neutral pulp a slight acidity or even alkalinity with some ores is not detrimental to the general results obtained by my invention. .The instrumentalities employed in practicing my process are not important, any suitable flotation machine capable of preserving the working conditions essential to the success of the process answering ,the purpose. In the drawings, I show one ty eof machine but other types may be used The details of the invention will now be described in connection with the accompanying drawings in which Figure 1 represents a sideelevation of a concentrating tank or cell suitable for carrying on my new process, parts being in section; Fig. 2 is a top plan of Fig. 1 with parts broken away; and Fig. 3 is a diagrammatic side elevation showing three cells in series.

Referring to the drawings, 1 represents a suitable (preferably concrete) tank or cell provided with a stirring compartment or and a froth compartment 2), the two compartments bein separated by a partition wall w provide with a slot or circulating opening 0 near the center thereof, said 0 en ing extending the width of the cell, a slmilar but narrower circulating opening 0' being formed between the lower edge of the partition wall and the bottom of the cell. The froth compartment is preferably provided with an inclined wall w o posite the wall w, the said inclined wall heing pro vided with a transverse overflow edge e depressed below the side walls of the cell,

as shown (Fig. 2).

the froth h flowing over said edge into a launder 2 from which the froth is conducted to any suitable point for further treatment.v Leading from the inclined wall to near the base thereof is a spout 3 which discharges the tailings from the cell 1 into the stirring compartment a of a second cell 1, the vertical end wall of the latter being provided with a pulp inlet openlng m into which the spout 3 is inserted. The corresponding wall of the. cell 1 is provided with a pulp inlet m which may be coupled to any suitable source of pulp supply (not shown). Disposed transversely of the comartment a below the circulating opening 0 IS a stirrer or beater shaft 4:, the same being provided inside said compartment a with a series of radially disposed arms 5 to the outer ends of which are secured the perforated heaters or blades (i, the latter being disposed parallel to the axis of the shaft The outer edges of the blades are substantially opposite the center line of the opening 0 whenthey sweep, and opposite the opening 0 when at the lowest point of their downward sweep, this arrangement ensuring a thorough circulation of the beaten pulp through said openings, it being understood that the heaters revolve toward the opening 0 and from the opening 0 (counter-clockwise in Fig. 1). The top of each cell is provided with a hinged or equivalent lid L which closes air-tight when clamped down. The aerating medium or sulfureted hydrogen gas is contained in a gas tank 7 from which leads a pipe 8 to the compartment a through the top of the cell, a similar branch pipe 8 leading to the stirring compartment a of the cell -1', the pipes being provided at convenient points with controlling needle valves V of any approved pattern known to the art, the quantities of gas admitted to the cells being carefully regulated by said valves. In the example before us only two cells 1, 1, are shown but it is obvious that we may have a series of three (or more) cells 1, 1, 1", any cell receivin the tailin of the cell immediately prece ing, and discharging its concentrates or mineral froth into its own launder as shown in the diagrammatic illustration in Fig. 3. The heater shaft 4 extends .through the side walls of the cell being supported near the walls in bearings 9, the shaft extending beyond one of the bearings and carrying a pulley P from whichextends a belt B to a pulley P of the shaft of a suitable electric motor ,M. Any other method of driving the stirrer shaft may however he resorted to, and any suitable mechanical connections within the purview of the reach the highest point of their upward skilled mechanic may be employed to drive the stlrrers of the remaining cells of series. Since all the cells and their mode of operation are the same, a description of one will sulfice for all, and accordingly the description of the. operation of the process will be confined to the main or first cell 1 of the series. This operation is substantially as follows: 7

Pulp is fed tc the compartment a through the inlet m by a nozzle or pipe A leading from any suitable source of pulp supply (not shown), the lid L being clamped down so as to exclude the air, thereby promoting sulfidation and minimizing the danger of oxidation of the mineral particles sulfidized by the sulfureted hydrogen (assuming that wev are treating oxidized ores) admitted into the cell. At the same time, by a proper control of the valve V, suitable quantlties of sulfureted hydrogen under pressure are admitted into the compartment a, the beater been set into motion so that the pulp contents of the cell are not only beaten, but during the beating operation the gas above the pul being under pressure, impregnates the mo ecules of the eaten pulp, the mechanical agitation of the pulp assisting in effecting a thorough mixing thereof with, and aeration by, the gas, the bubbles resulting from the combination of operations rising through the liquid pulp in the compartment b where the portions of the pulp above the plane of the opening 0 are comparatively quiescent, the froth h, being a mineral froth (in contradistinction to an oil froth), floating on the surface of the pulp in the froth compartment 5 and flowing over the edgee into the launder 2. lhe beating or stirring of the pulg in the compartment a causes the llqui to circulate between the compartments a, b, substantially as indicated by the arrows in Fig. 1, and as more pulp is added to the charge more froth is formed and carried away by the launder 2. The tailings from cell 1 are constantly, discharging through the spout 3 into the next cell where the same are subjected to like treatment. These tailings not only include sands or gangue having no value, but considerable mlneral matter which has escaped treatment in the first cell. After the pulp has traversed a number of cells, the tailings from the last cell are discarded containing as they do only the gangue with perhaps a, negligible amount of mineral. Obviously, and especially for the reason that the sulfureted hydrogen is under pressure, the level of the li uid in the cell must be kept above the in et m; otherwise the gas would escape from the cell. It is even possible-that the level of the pulp in the compartment a may be depressed below that in the compartment 1), by the pneumatic pressure of the gas above the-liquid in the compartment a; but ohdency to oversulfidation of any given charge of ore operated on, especially in cases where natural mineral sulfids are associated with the oxidized ores (carbonates, oxids, silicates) undergoing sulfida tion for purposes of making froth. The gas may be cut off at "the tank 7 by means of an ordinary globe valve V well understood in the art. The precise chemical reactions which take place .in the cell need not be gone into because or stirrer shaft having in the meant1me varying with different charges of pulp, but in a general way it may be stated that in treating what are known as oxidized ores (as distinguished from sulfids) these are sulfidized by the sulfureted hydrogen to the extent necessary to form an outer coat of sulfid on the larger mineral particles (the ore being. ground to the usual degree of fineness as. practiced in the flotation arltf)l the smallest particles being possibly su dized all the way to the center. The prevailing ores treated are oxidized ores of copper, zinc, and lead, though chlorid of silvermay likewise be successfully floated by my process. The bases of any metallic salts that may be held in solution by the pulp waters may likewise be sulfidized (usually in the form of precipitates of the sulfids of the metals) and floated with the main bulk of sulfidized particles derived from the oxidized mineral particles held in suspension in the pulp water. In all cases oversulfidation, or sulfidation to or beyond the point of saturation should be avoided, as the formation of saturated sulfids in many cases increases the specific gravity of the mineral particles as compared with, their specific gravity inv the oxidized or semioxidized and sulfidized state, and hence renders them less susceptible to flotation than in those cases where the sulfidation is arrested at a point where the specific gravity of the mineral particle is still comparatively low. Of course the point to which the sulfidation shall be carried depends on the ore treated, and every new ore should first be tested in this regard. In the majority of cases the mineral froth formed by the sulfureted hydrogen is 'suficiently coherent to maintain its integrity while being floated to and out of the froth launder 2, but should it be desirable to render the froth more elastic, a pinch of rosin may be added to stantly churn the contents of the cell, and thereby cause different particles of the ulp to present themselves to the superincum ent body of gas in'the compartment a until the entireiliquid body is impregnated with the gas which upon its release in the compartment b-rises to the surface in bubble form taking with it the sulfidized mineral particles in the form of a; coherent mineral froth. The process is likewise applicableto sulfid ores but obviously the amount of sulfurcted hydrogen used would be'materially reduced as compared with that employed in connection with oxidized era that must first be sulfidized before vthey will attach themselves to the bubbles formed by the gas with which the'pulp is'charged.

Having describedmyinvention what I claim is In the concentration o f -ores', the process which consists in subjecting a charge of ore in pulp form While under agitation to the actlon of sulfureted hydrogen maintained under pressure against the pulp mass to the exclusion of other selective agents and out of contact with the atmosphere to sulfidize the mineral particles andaerate the pulp mass, then cutting off the supply of hydrogen sulfid, and continuing the agitation in contact with the air atnormal atmospheric pressure, causing the resultin bubbles and mineral particles adhering t ereto to migrate through the pulp to a region of comparative quietyand removing the resulting froth fr'omthe surface of said region.

In testimony whereof I afiix my signature, in presence of two witnesses.

J. A. CAMEL, ELLA QHARA. 

